Protective casing for electrical equipment

ABSTRACT

Protective casing ( 10 ) for electrical equipment which is to be deployed in a hazardous environment comprises a main body portion ( 12, 14 ) and one or more protective cages each comprising at least one annulus ( 20 A) surrounding the main body portion and attached thereto by two or more spoke members ( 20 ). The invention provides casing which conforms to applicable standards whilst being simple and inexpensive to manufacture.

FIELD OF THE INVENTION

[0001] The invention relates to protective casing for electronicequipment, particularly for electrical equipment which is required to bedeployed in hazardous environments, for example toxic or potentiallyexplosive environments.

BACKGROUND TO THE INVENTION

[0002] Certain minimum standards apply to electrical equipment for usein hazardous environments, for example electrical apparatus for use inpotentially explosive environments is regulated in the European Union(EU) by EU standards BS EN 50018, BS EN 50016 and BS EN 50020, and inthe United States by US standards UL 1203, US 913 and UL 6500. Similarstandards apply to electrical apparatus for use in toxic environments,such as inside chemical and petroleum tanks. Inter alia these standardsspecify a minimum impact force which an electrical apparatus must beable to withstand.

[0003] Previously it has proved difficult and expensive to provideprotective casing for electrical apparatus for use in hazardousenvironments, which casing simultaneously meets the requirements of allapplicable standards.

OBJECT OF THE INVENTION

[0004] The invention seeks to provide an improved protective casing forelectronic equipment which mitigates at least one problem associatedwith the prior art.

SUMMARY OF THE INVENTION

[0005] According to the present invention, there is provided aprotective casing, in which a protective cage comprising an annulussurrounds a main body portion of the casing, and at least two spokemembers attach the annulus to the main body portion.

[0006] In particular there is provided a protective casing forelectrical equipment, the casing comprising a main body portion adaptedto receive the equipment, and having a protective cage comprising atleast one annulus surrounding the main body portion, and at least twospoke members attaching the annulus to the main body portion.

[0007] To provide enhanced impact protection for a relatively smalladditional weight and cost penalty, the cage may comprise two likeannuli which surround the main body portion at different longitudinalpositions along the main body portion, which define substantiallyparallel planes and which are attached to the main body portion by atleast two common spoke members.

[0008] Preferably the or each annulus is circular in shape, providingfor simpler manufacture and allowing the casing to roll on a flatsurface.

[0009] If the or each annulus has a length in a dimension parallel tothe length of the main body portion equal to approximately 10% of thelength of the main body portion, good impact protection is provided butthe overall weight of the casing is not excessive.

[0010] Preferably the or each annulus, and the main body portion, arewelded to the spoke members as this provides a particularly strongcasing.

[0011] To provide still further impact protection, casing of theinvention may comprise two or more protective cages.

[0012] To provide still further impact protection, the spoke members andthe, or each, annulus, may be arranged to be resiliently flexible.

[0013] Preferably the or each annulus is attached to the main bodyportion by three or more spoke members in order to give enhancedrigidity to the one or more protective cages.

[0014] The preferred features may be combined as appropriate, as wouldbe apparent to a skilled person, and may be combined with any of theaspects of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] An embodiment of the present invention is described below, by wayof example only, with reference to the accompanying drawings in which:

[0016]FIG. 1 is a side view of a protective casing of the invention fora video camera which is intended for deployment inside chemical tank;

[0017]FIG. 2 is a perspective view of the FIG. 1 casing; and

[0018]FIG. 3 is a longitudinal cross-section through the FIG. 1 casing,the plane of the section being substantially a diametrical plane throughthe casing.

DETAILED DESCRIPTION OF INVENTION

[0019] Referring to the Figures, a protective casing, according to theinvention, for a video camera intended for deployment inside a hazardouschemical tank is indicated generally by 10. The casing 10 comprises amain body portion having first 12 and second 14 co-axial cylindricalsections which, as indicated in FIG. 3, incorporate hollow enclosures13, 15 for receiving a video camera. The cylindrical sections 12, 14 areformed of stainless steel 316 S11, for example. The casing 10 furthercomprises first 16 and second 17 end caps for sealing the main bodyportion after a video camera has been inserted so as to occupy theenclosures 13, 15. End cap 16 incorporates a connector on its exteriorto allow video data to pass from the camera, through the casing 10, to aremote location. End cap 17 incorporates a glass window (not shown)enabling light to pass through the casing 10 to the video camera (notshown).

[0020] The casing 10 further comprises first 18 and second 20 protectivecages attached to and surrounding the exterior of cylindrical sections12 and 14 respectively.

[0021] Cage 18 comprises a substantially circular metal annulus 18Ahaving an internal diameter greater than the external diameter of thefirst cylindrical section 12 of the casing 10, and is fixed tocylindrical section 12 by two or more spoke members 18S which are TIGwelded thereto.

[0022] Protective cage 20 comprises two substantially circular metalannuli 20A, 20B surrounding the exterior of the cylindrical section 14and TIG welded thereto by at least two common spoke members 20S. Theannuli 20A, 20B each have an internal diameter greater than the externaldiameter of the second cylindrical section 14, and are parallel andseparated by a distance approximately equal to the length of thecylindrical section 14.

[0023] The annuli 18A, 20A, 20B and the spoke members 18S, 20S areresilient, allowing shock absorption, and hence a reduced risk of damageto the video camera, if the casing 10 is dropped onto a hard surface.

1. Protective casing for electrical equipment, the casing comprising amain body portion adapted to receive the equipment, and having aprotective cage comprising at least one annulus surrounding the mainbody portion, and at least two spoke members attaching the annulus tothe main body portion.
 2. Casing according to claim 1 wherein the cagecomprises two like annuli which surround the main body portion atdifferent longitudinal positions along the main body portion, whichdefine substantially parallel planes and which are attached to the mainbody portion by at least two common spoke members.
 3. Casing accordingto claim 1 wherein the at least one annulus is substantially circular inshape.
 4. Casing according to claim 1 wherein the at least one annulushas a length in a dimension parallel to the length of the main bodyportion equal to approximately 10% of the length of the main bodyportion.
 5. Casing according to claim 1 wherein at least one annulus andthe main body portion, are welded to the spoke members.
 6. Casingaccording to claim 1 comprising two or more protective cages.
 7. Casingaccording to claim 1 comprising three or more spoke members.
 8. Casingaccording to claim 1 wherein the spoke members and the at least oneannulus are resilient.
 9. Protective casing for electrical equipment,the casing comprising a main body portion adapted to receive theequipment, characterised by a protective cage comprising at least oneannulus surrounding the main body portion, and at least two spokemembers attaching the annulus to the main body portion, wherein the cagecomprises two like annuli which surround the main body portion atdifferent longitudinal positions along the main body portion, whichdefine substantially parallel planes and which are attached to the mainbody portion by at least two common spoke members and wherein the atleast one annulus has a length in a dimension parallel to the length ofthe main body portion equal to approximately 10% of the length of themain body portion.